Multi stage peroxide and activated peroxide bleaching of kenaf bast pulp.

Soda-anthraquinone kenaf bast pulp (12.5 kappa number and 32% ISO brightness) has been bleached with multi stage peroxide bleaching process. Bleaching process was carried out in different sequences of peroxide stage without and with activator (tetraacetylethylenediamine, TAED) to about 80% ISO brightness. Full bleached pulp production with high brightness and viscosity and also, low chemical oxygen demand (COD) and no adsorbable organic halogens (AOX) in effluent are the aims of this study. The effects of temperature, retention time, chemical charges, TAED/peroxide ratio and alkalinity have been studied in order to maximize the brightness gain at the lowest viscosity loss. H(2)O(2) was activated as bleaching agent under milder conditions, such as low alkalinity or low temperature, by TAED activator. Therefore, TAED charge caused to an improvement in viscosity, pulp yield and effluent COD load. Pre-treatment with EDTA for 30 min and in acidic condition gave 2-4% gain in ISO brightness.